1. Field of the Invention
The present invention relates to a conductive connecting member connected to electric wire with insulating coating by a fusing process so that electric continuity is ensured, and an electric motor provided with the conductive connecting member.
2. Description of the Related Art
There is an electric motor (or motor) used for a hybrid vehicle or the like. This electric motor includes a stator having a plurality of stator cores formed so as to be divided in a circumferential direction, and a rotor rotatably placed relative to the stator, as disclosed in Japanese Patent Application Publication No. 2005-229677, for example. A stator coil (winding) is wound up around each stator core. Further, a bus ring for connecting the stator coils of the respective phases to each other is placed on an outer circumference of the stator. A conductive connecting member (conductive connecting terminal) for electrically connecting a terminal of the bus ring to a winding end of the stator coil is placed at an outer circumference side of the stator coil. This conductive connecting member is a strip-like member made of metallic material. The conductive connecting member has a connecting section for connecting a terminal of the bus ring thereto at one end, and a connecting section for connecting the winding end of the stator coil thereto at the other end. Each of these connecting sections is a portion formed by bending end portions of the conductive connecting member so that a cross section thereof becomes a U shape.
Now, of stator coils and electric wire of bus rings, there are ones with insulating coating on a surface thereof. In the case where a winding end of a stator coil or a terminal of a bus ring using electric wire with such insulating coating is bonded to a conductive connecting member, a fusing (thermal caulking) process for conducting a bonding point is required. In the fusing process, the electric wire is held by being clipped inside a U-shaped connecting section to pressurize the connecting section from both sides, and at that state, a current for fusing flows between the connecting section and the electric wire. This causes insulating coating of a surface of the electric wire to be melted, whereby a bonded surface is welded (fused).
In the fusing process as described above, insulating coating melted on the bonded surface between a conductive connecting terminal and the electric wire becomes a product containing carbide and the like, called sludge (in this specification, called “carbonized insulator”). This carbonized insulator is stuck mainly around the bonded surface between the conductive connecting terminal and the electric wire, but remains on the bonded surface. This causes electrical resistance of the bonded surface between the conductive connecting terminal and the electric wire to become large, and therefore, there has been a fear to bring the generation of heat at a bonding point or drop of efficiency of the electric motor. Further, joint strength between the conductive connecting terminal and the electric wire is lacking, whereby vibration resistance is lowered, or corrosion by aging degradation occurs easily. There has been a fear that this has an influence on durability of the electric motor. For that reason, there is need to eliminate carbonized insulator generated in a fusing process from a bonded surface between a conductive connecting terminal and electric wire as much as possible.